In portable computers and word processors, for example, the positioning angle of a display device can be adjusted by a shaft locking device.
In the conventional shaft locking device, an end of a shaft is attached into a cylindrical member, and a coil spring is disposed outside the shaft and the cylindrical member. The spring has an inner diameter slightly smaller than the outer diameters of the shaft and the cylindrical member, and both ends of the coil spring are free ends.
Such a conventional shaft locking device mentioned above has a structure in which slip is generated between the coil spring and the shaft so that the shaft is greatly worn. To overcome this problem, it is necessary to harden the contact surfaces of the shaft and the coil spring, thereby increasing the cost of the apparatus. Further, the weight of the apparatus is increased, and the strict accuracy of the size of the apparatus is required since the slipping action is utilized in a direction in which the coil spring is fastened, thereby reducing the yield.